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1da177e4 LT |
1 | /* |
2 | * linux/fs/hfsplus/bitmap.c | |
3 | * | |
4 | * Copyright (C) 2001 | |
5 | * Brad Boyer (flar@allandria.com) | |
6 | * (C) 2003 Ardis Technologies <roman@ardistech.com> | |
7 | * | |
8 | * Handling of allocation file | |
9 | */ | |
10 | ||
11 | #include <linux/pagemap.h> | |
12 | ||
13 | #include "hfsplus_fs.h" | |
14 | #include "hfsplus_raw.h" | |
15 | ||
16 | #define PAGE_CACHE_BITS (PAGE_CACHE_SIZE * 8) | |
17 | ||
18 | int hfsplus_block_allocate(struct super_block *sb, u32 size, u32 offset, u32 *max) | |
19 | { | |
20 | struct page *page; | |
21 | struct address_space *mapping; | |
22 | __be32 *pptr, *curr, *end; | |
23 | u32 mask, start, len, n; | |
24 | __be32 val; | |
25 | int i; | |
26 | ||
27 | len = *max; | |
28 | if (!len) | |
29 | return size; | |
30 | ||
31 | dprint(DBG_BITMAP, "block_allocate: %u,%u,%u\n", size, offset, len); | |
1b1dcc1b | 32 | mutex_lock(&HFSPLUS_SB(sb).alloc_file->i_mutex); |
1da177e4 | 33 | mapping = HFSPLUS_SB(sb).alloc_file->i_mapping; |
090d2b18 | 34 | page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL); |
649f1ee6 ES |
35 | if (IS_ERR(page)) { |
36 | start = size; | |
37 | goto out; | |
38 | } | |
1da177e4 LT |
39 | pptr = kmap(page); |
40 | curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32; | |
41 | i = offset % 32; | |
42 | offset &= ~(PAGE_CACHE_BITS - 1); | |
43 | if ((size ^ offset) / PAGE_CACHE_BITS) | |
44 | end = pptr + PAGE_CACHE_BITS / 32; | |
45 | else | |
46 | end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32; | |
47 | ||
48 | /* scan the first partial u32 for zero bits */ | |
49 | val = *curr; | |
50 | if (~val) { | |
51 | n = be32_to_cpu(val); | |
52 | mask = (1U << 31) >> i; | |
53 | for (; i < 32; mask >>= 1, i++) { | |
54 | if (!(n & mask)) | |
55 | goto found; | |
56 | } | |
57 | } | |
58 | curr++; | |
59 | ||
60 | /* scan complete u32s for the first zero bit */ | |
61 | while (1) { | |
62 | while (curr < end) { | |
63 | val = *curr; | |
64 | if (~val) { | |
65 | n = be32_to_cpu(val); | |
66 | mask = 1 << 31; | |
67 | for (i = 0; i < 32; mask >>= 1, i++) { | |
68 | if (!(n & mask)) | |
69 | goto found; | |
70 | } | |
71 | } | |
72 | curr++; | |
73 | } | |
74 | kunmap(page); | |
75 | offset += PAGE_CACHE_BITS; | |
76 | if (offset >= size) | |
77 | break; | |
090d2b18 PE |
78 | page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, |
79 | NULL); | |
649f1ee6 ES |
80 | if (IS_ERR(page)) { |
81 | start = size; | |
82 | goto out; | |
83 | } | |
1da177e4 LT |
84 | curr = pptr = kmap(page); |
85 | if ((size ^ offset) / PAGE_CACHE_BITS) | |
86 | end = pptr + PAGE_CACHE_BITS / 32; | |
87 | else | |
88 | end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32; | |
89 | } | |
90 | dprint(DBG_BITMAP, "bitmap full\n"); | |
91 | start = size; | |
92 | goto out; | |
93 | ||
94 | found: | |
95 | start = offset + (curr - pptr) * 32 + i; | |
96 | if (start >= size) { | |
97 | dprint(DBG_BITMAP, "bitmap full\n"); | |
98 | goto out; | |
99 | } | |
100 | /* do any partial u32 at the start */ | |
101 | len = min(size - start, len); | |
102 | while (1) { | |
103 | n |= mask; | |
104 | if (++i >= 32) | |
105 | break; | |
106 | mask >>= 1; | |
107 | if (!--len || n & mask) | |
108 | goto done; | |
109 | } | |
110 | if (!--len) | |
111 | goto done; | |
112 | *curr++ = cpu_to_be32(n); | |
113 | /* do full u32s */ | |
114 | while (1) { | |
115 | while (curr < end) { | |
116 | n = be32_to_cpu(*curr); | |
117 | if (len < 32) | |
118 | goto last; | |
119 | if (n) { | |
120 | len = 32; | |
121 | goto last; | |
122 | } | |
123 | *curr++ = cpu_to_be32(0xffffffff); | |
124 | len -= 32; | |
125 | } | |
126 | set_page_dirty(page); | |
127 | kunmap(page); | |
128 | offset += PAGE_CACHE_BITS; | |
090d2b18 PE |
129 | page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, |
130 | NULL); | |
649f1ee6 ES |
131 | if (IS_ERR(page)) { |
132 | start = size; | |
133 | goto out; | |
134 | } | |
1da177e4 LT |
135 | pptr = kmap(page); |
136 | curr = pptr; | |
137 | end = pptr + PAGE_CACHE_BITS / 32; | |
138 | } | |
139 | last: | |
140 | /* do any partial u32 at end */ | |
141 | mask = 1U << 31; | |
142 | for (i = 0; i < len; i++) { | |
143 | if (n & mask) | |
144 | break; | |
145 | n |= mask; | |
146 | mask >>= 1; | |
147 | } | |
148 | done: | |
149 | *curr = cpu_to_be32(n); | |
150 | set_page_dirty(page); | |
151 | kunmap(page); | |
152 | *max = offset + (curr - pptr) * 32 + i - start; | |
153 | HFSPLUS_SB(sb).free_blocks -= *max; | |
154 | sb->s_dirt = 1; | |
155 | dprint(DBG_BITMAP, "-> %u,%u\n", start, *max); | |
156 | out: | |
1b1dcc1b | 157 | mutex_unlock(&HFSPLUS_SB(sb).alloc_file->i_mutex); |
1da177e4 LT |
158 | return start; |
159 | } | |
160 | ||
161 | int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count) | |
162 | { | |
163 | struct page *page; | |
164 | struct address_space *mapping; | |
165 | __be32 *pptr, *curr, *end; | |
166 | u32 mask, len, pnr; | |
167 | int i; | |
168 | ||
169 | /* is there any actual work to be done? */ | |
170 | if (!count) | |
171 | return 0; | |
172 | ||
173 | dprint(DBG_BITMAP, "block_free: %u,%u\n", offset, count); | |
174 | /* are all of the bits in range? */ | |
175 | if ((offset + count) > HFSPLUS_SB(sb).total_blocks) | |
176 | return -2; | |
177 | ||
1b1dcc1b | 178 | mutex_lock(&HFSPLUS_SB(sb).alloc_file->i_mutex); |
1da177e4 LT |
179 | mapping = HFSPLUS_SB(sb).alloc_file->i_mapping; |
180 | pnr = offset / PAGE_CACHE_BITS; | |
090d2b18 | 181 | page = read_mapping_page(mapping, pnr, NULL); |
1da177e4 LT |
182 | pptr = kmap(page); |
183 | curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32; | |
184 | end = pptr + PAGE_CACHE_BITS / 32; | |
185 | len = count; | |
186 | ||
187 | /* do any partial u32 at the start */ | |
188 | i = offset % 32; | |
189 | if (i) { | |
190 | int j = 32 - i; | |
191 | mask = 0xffffffffU << j; | |
192 | if (j > count) { | |
193 | mask |= 0xffffffffU >> (i + count); | |
194 | *curr++ &= cpu_to_be32(mask); | |
195 | goto out; | |
196 | } | |
197 | *curr++ &= cpu_to_be32(mask); | |
198 | count -= j; | |
199 | } | |
200 | ||
201 | /* do full u32s */ | |
202 | while (1) { | |
203 | while (curr < end) { | |
204 | if (count < 32) | |
205 | goto done; | |
206 | *curr++ = 0; | |
207 | count -= 32; | |
208 | } | |
209 | if (!count) | |
210 | break; | |
211 | set_page_dirty(page); | |
212 | kunmap(page); | |
090d2b18 | 213 | page = read_mapping_page(mapping, ++pnr, NULL); |
1da177e4 LT |
214 | pptr = kmap(page); |
215 | curr = pptr; | |
216 | end = pptr + PAGE_CACHE_BITS / 32; | |
217 | } | |
218 | done: | |
219 | /* do any partial u32 at end */ | |
220 | if (count) { | |
221 | mask = 0xffffffffU >> count; | |
222 | *curr &= cpu_to_be32(mask); | |
223 | } | |
224 | out: | |
225 | set_page_dirty(page); | |
226 | kunmap(page); | |
227 | HFSPLUS_SB(sb).free_blocks += len; | |
228 | sb->s_dirt = 1; | |
1b1dcc1b | 229 | mutex_unlock(&HFSPLUS_SB(sb).alloc_file->i_mutex); |
1da177e4 LT |
230 | |
231 | return 0; | |
232 | } |